How Do I Soften Up White Chocolate Ganache?

I made w batch of white chocolate ganache, and it turned out really well but now I'd like to use the left overs as a cupcake filling, but I need it to be softer. Right now it's a little too thick - is there anything I can add to it to make it a bit lighter and fluffier? Butter? Cream? Oh, and just to let you know it's already whipped.